Radial Engineering Tonebone JX-2 Switchbone User Manual page 3

1. INTRODUCTION
The Radial JX2 Switchbone was born from the demand we received from
users like you. The Switchbone is in fact a pared down version of the
popular Radial JD7 Injector, a studio recording device that allows as many
as 7 amplifiers to be driven from one guitar.
The Switchbone has been optimized for stage use and allows a guitar to
drive two amplifiers and a tuner from one guitar input and do it without
introducing buzz, hum, or distortion.
Sounds easy enough... but it is not. For those that have tried connecting
two amplifiers together using Y-cords or some of the other AB-Y boxes
that have come before, you are familiar with the many challenges:
Drop in gain, tone changes, buzz and hum just to name a few. The
Radial Switchbone is a remarkable device that deals with all of these
problems and brings forth a design that is easy to use, musical and
truly effective.
Please take the time to read this manual before you plug in. It will help you
get the most out of your Radial Switchbone and also eliminate potential
shock hazards that can occur when connecting equipment together.
2. CONCEPT
The Radial Switchbone begins with the concept that most 'tone crazy'
players will generally use two amps on stage. (Of course more is better,
but then someone would have to carry all those amps to the gigs!)
When one drives two amplifiers with one guitar, the signal from the pickup
is divided in two and the sound changes. To get around this problem,
the Switchbone employs a unique Class-A amplifier circuit that has been
optimized for use with guitars. With customers like Eric Johnson, Carlos
Santana and Neal Schon, we are not allowed to alter the sound of their
favorite vintage axe. The sound must be real!
This leads to the next problem: Your guitar has now gone from being
passive to essentially becoming active. Your pickup is no longer
connected directly to the amplifier. It is being 'buffered' (amplified). The
natural relationship is lost. To compensate for this, we have introduced
a feature called Drag™ control to allow you to reintroduce the natural
loading that is lost. With load-correction, the instrument goes back to
normal. It breathes!
Finally as soon as you connect two amplifiers together they hum, they
buzz and sometimes even spark with hundreds of volts! This is due
to the way that each manufacturer builds their amplifiers. Some use
positive ground, others negative. Some use the chassis as a ground
plane and some old designs from the 50's and 60's that do not have
proper 3-pin safety U grounds. The Radial Switchbone incorporates a
transformer isolated output, a ground lift switch and a polarity reverse
switch to allow your two amplifiers to be used in tandem. These are
designed to separate and isolate the electrical current of each amplifier
and eliminate ground loops.
Radial Engineering Ltd.
3
True to the Music
Switchbone ™ Users Guide
Of course, once you get these amps connected together, you have
to control them! This is where the Switchbone also shines! The
Switchbone is easy to use. The foot switch layout and LED readout
follows a 'common sense' and intuitive approach that is very natural.
We have also added a boost circuit to allow you to 'step-up' the output
to both amps simultaneously for a solo or extra saturation when playing
through a distorted sound. We have even added a separate output for
your tuner. This also takes the tuner out of the audio circuit thus ensuring
you get the direct tone of your guitar.
CAUTION:
When connecting two amplifiers together you must ensure that they are
properly grounded as per the electrical code!
Unfortunately, we are unable to test every amplifier on the market and
cannot assure that the electrical system in your house or venue has been
wired correctly. You must ensure that proper electrical codes have been
maintained and only equipment that has been certified by your country's
electrical code is being used.
An important note about grounding:
Since guitar circuits are high-gain and high impedance,
RF noise, hum and buzz are easily induced. Connecting
equipment with different grounding schemes often results in
ground loops and more noise. The Radial JX2 addresses
these problems by employing a floating ground architecture
which requires an earth ground. This is accomplished via
the Channel-1 output. Channel-1 provides an electrical
ground from the JX2 chassis to the primary guitar amplifier,
therefore always connect Channel-1 to a guitar amp with
a 3-prong grounded A/C power cord to enable a proper
ground and keep noise out.
To ensure an ungrounded (2 prong) amplifier does not
present a shock hazard: Test for voltage potential by con-
necting a voltmeter between the amplifier chassis and the
JX2 chassis. If voltage is present, reverse the amplifier's
A/C supply polarity and test again.
Radial Engineering Ltd.
4
True to the Music
Switchbone ™ Users Guide